Enhanced flight planning and calibration for UAV based thermal imaging: implications for canopy temperature and transpiration analysis DOI Creative Commons

Malkin Gerchow,

Kathrin Kühnhammer,

Alberto Iraheta

et al.

Frontiers in Forests and Global Change, Journal Year: 2025, Volume and Issue: 8

Published: March 4, 2025

Leaf and canopy temperature have long been recognized as important indicators of plant water status because leaves cool when is transpired warm up leaf stomata close transpiration reduced. Unmanned aerial vehicles (UAVs) open the possibility to capture high resolution thermal images forest canopies at scale. However, a careful calibration procedure required convert absolute temperatures, in addition, spatial resolution, complexity leads challenges stitching overlapping into an orthomosaic site. In this study, we present novel flight planning approach which locations ground references are directly integrated plan. Six UAV campaigns were conducted over tropical dry Costa Rica. For each five different methods tested. The most accurate was used analyze tree distributions species. From distribution correlated its mean, variance, 5th 95th percentile against individual estimates derived from sapflow measurements. Our results show that commonly applied provided by cameras manufacturer (factory calibration) empirical line less than repeated factory including drift correction (MAE 3.5°C vs. MAE 1.5°C). We computable estimating image orientation visible during structure motion step. found distribution, corresponding shaded within canopy, be better predictor mean (R 2 0.85 R 0.60). Although these not representative whole they may main site heat day. Spatially high-resolution, validated data scale many applications for ecohydrological questions, e.g., estimation transpiration, comparing traits modeling carbon fluxes considering entire mixed-species forests.

Language: Английский

Enhanced flight planning and calibration for UAV based thermal imaging: implications for canopy temperature and transpiration analysis DOI Creative Commons

Malkin Gerchow,

Kathrin Kühnhammer,

Alberto Iraheta

et al.

Frontiers in Forests and Global Change, Journal Year: 2025, Volume and Issue: 8

Published: March 4, 2025

Leaf and canopy temperature have long been recognized as important indicators of plant water status because leaves cool when is transpired warm up leaf stomata close transpiration reduced. Unmanned aerial vehicles (UAVs) open the possibility to capture high resolution thermal images forest canopies at scale. However, a careful calibration procedure required convert absolute temperatures, in addition, spatial resolution, complexity leads challenges stitching overlapping into an orthomosaic site. In this study, we present novel flight planning approach which locations ground references are directly integrated plan. Six UAV campaigns were conducted over tropical dry Costa Rica. For each five different methods tested. The most accurate was used analyze tree distributions species. From distribution correlated its mean, variance, 5th 95th percentile against individual estimates derived from sapflow measurements. Our results show that commonly applied provided by cameras manufacturer (factory calibration) empirical line less than repeated factory including drift correction (MAE 3.5°C vs. MAE 1.5°C). We computable estimating image orientation visible during structure motion step. found distribution, corresponding shaded within canopy, be better predictor mean (R 2 0.85 R 0.60). Although these not representative whole they may main site heat day. Spatially high-resolution, validated data scale many applications for ecohydrological questions, e.g., estimation transpiration, comparing traits modeling carbon fluxes considering entire mixed-species forests.

Language: Английский

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